Monitoring systems for the railroad industry provide methods and apparatus for automatic determination of the conditions of wheels and bearings on passing trains. Infrared (IR) scanners and associated circuits are available commercially and are used in close proximity to railroad tracks at wayside stations or in housings formed to mount on or replace certain ties. Existing IR scanners use a lens or other optical apparatus to collect radiated infrared energy from the wheels or wheel bearings and focus the collected infrared radiation directly onto an infrared detection device, such as a pyroelectric cell or a focal plane array (FPA) of such cells. The pyroelectric cell(s) produces an output voltage that is proportional to the infrared temperature of the infrared radiation passing through the detector's optics. An increase in the power or intensity of the infrared radiation results in an increase in the voltage or current generated by the detector. Known IR scanners sense infrared radiation radiating from the wheels or wheel bearings within two or more infrared wavelength ranges.
One problem associated with existing monitoring systems is the lack of accuracy in the detection of temperatures of different types and sizes of wheel bearings or other objects or components having inconsistent configurations as they pass an infrared scanner. New methods of monitoring the conditions of components on trains call for accurate identification of trends in the temperature of a component on the train as the component passes successive detectors positioned along the railroad tracks in the direction of train travel. For example, different size and configuration wheel bearings such as “F” type wheel bearings and “K” type wheel bearings have different dimensions from the front edge to the back edge of the bearings, and therefore different relative locations of portions of the wheel bearings such as the grease seal backing ring, which may be expected to run at hotter temperatures than the rest of the bearing.
One attempt to improve the accuracy of detection of a temperature range or a temperature of a wheel or wheel bearing on a train is disclosed in U.S. Pat. No. 6,872,945 of Bartonek that issued on Mar. 29, 2005 (the '945 patent). The '945 patent provides a sensor that senses infrared radiation radiating from a wheel or wheel bearing within two or more different infrared wavelength ranges, and generates signals indicative of an amplitude of the sensed infrared radiation in each of the wavelength ranges. The sensor receives infrared radiation originating from a source or point of origin, and includes an array of a plurality of infrared detection elements. Each of the infrared detection elements is configured to detect a separate and unique wavelength range or frequency band of radiation that does not overlap with any wavelength range of any other element. A peak wavelength range is determined with the greatest amplitude, and this peak wavelength range is indicative of the temperature of the wheel or wheel bearing.
Although the temperature detection system of the '945 patent improves the accuracy of detection of a temperature of a wheel or wheel bearing by detecting peak wavelength ranges that are not affected by external factors such as snow, ice, rain, wind, or sun, it may be less than optimal. In particular, the detection system may focus on a limited area of the passing wheel bearing, and may therefore provide a less than optimal temperature or temperature profile for components such as wheel bearings that often vary in configuration. This inaccuracy in measuring the temperature of some passing wheel bearings also limits the ability to accurately identify trends in the temperatures that may be useful in predicting potential problems.
The system and method of the present disclosure solves one or more problems set forth above and/or other problems in the art.